Lapping machine



E. J. BULLARD LAPPING MACHINE Aug. 30, 1949.

4 Shee'ts-Sheet 1 Filed Nov. 28, 1945 IIWEN TOR: z'mi J fiullard,

ATTOR/VEX E J. BULLARD LAPPING MACHINE 4 Sheets-Sheet 2 INVENTOR:

Z'QI'Z JBuZZar Aug. 30, 1949.

Filed Nov; 28, 1945 Aug. 30, 1949. E. J. BULLARD 2,480,285

I LAPPING MACHINE Filed Nov. 28, 1945 4 Sheets-Shet 4 gzx III Ill/III VIII/1. 111

INVENTOR: Earl Jfiulzmz,

A TTOR/VEX Patented Aug. 30, 1949 PATENT OFFICE j l V V n 52,480,285 f g LAPPINGMACHINE Earl J. Bullard. Altadena, Calif.

'Applicatiiin"ngvembei 28, 1945, Serial No. 631,254

- 1 Claim. (Cl. 51-123) v The present invention chines. I j An object of the invention is to provide a means for moving the work over a lap in such relatesto lapping ma- 'a ma nher-that all parts of the lap are covered.

Another object of the invention is to provide a lapping machine adapted to hold work of various depths, V i Ariothe'r' object 1' to provide a lapping machine utilizing work holders wherein the Work holders maybe located on the lap'at any selected location: W U Anotlrier object is to provide in a lapping machine a construction wherein the lap maintains a predetermined surface whilein use. 'Another object is to provide in -'a lapping ma chine a lap so constructed and arranged that particles from the work are cleared, to the end that the workis not scratched or abraded. 'Anotherobject-isto provide ina lapping machine means whereby grit may be constantly conveyed to the surface of the lab.

Lapping machines now known tothe inventor require frequent dressing of the. lap to maintain thesame in a predetermined condition, for instance absolutely fiat. As the work, which is generally placed in a work. holder, is ground by the'lapduring, rotation of.the.lap, the lap wears unevenly. fCertainlappin machines, in an en- .deavorto overcome this defect; have attempted to havea sweeping movement of the work over the lapas the lap rotates. However, this does not prevent the lap'jrom wearing unevenly, with .the,resultthat after a short periodof time the lap 'must either be removed from, the machine and. resurfaced, or special dressing is applied to the 'lapsurface while on themachine. Such a resurfacing operation is long and tedious and requires the utmost ofeskill in the dressing operation. My invention automatically, maintains the lap surface in condition during the grinding of work, hence no. shutdown for a dressing operation.. I.

w The invention also contemplates the use of a lapv which is dressed on both surfaces, so that when one surface wears to a certain depth the lapgmay'be turne'dvover and the other surface used; Both "surfaces are so constructed that they remove grid and particles fromthe lap surface during the operation of the labs.

oithe i 1'. 2 g chine looking in the direction of the arrow 2 ofFigfll; 7

Fig. 3 is a plan view of a Wearring and disc whichmay be utilized in the practice of the in- Vention; 1 H v V Fig. 4 is a sectional view on the line 4-4 of Fig. 5 is a plan view showing the work "within the ring shown in Fig. 3; I f f. f Fig. 6 is a fragmentary elevation, partly-in sec tion, of the lapping machine and looking in the direction of the arrow 6 in Fig. 1; 7

Fig. 7 is an'elevat'ion, partly in section," of a tank for holding grinding compound utilized in I the practice of the invention; I Fig. 8 is afragmentary view, partly in section, and on an-enlarg'ed scale, on the line 8-'-'-B of Fig.

Fig. 9 is a fragmentary sectional view on an enlarged scale taken on the line 9- 9 of Fig. 6; Fig. '10 is a fragmentary sectional view 'on an enlarged scale on the line l0l0 of Fig; 6; Fig. 11' is a fragmentary, partially sectional view on an enlarged scale taken onthe line I |'-H of Fig. 1 and looking inthe direction of the arrows; and, L i

Fig. 12 is a plan'viewof a wiper to be'utilized in the tank of. Fig. '7. Referring now'with particularity to the drawingst The improved lapping machine includes alap I, adapted to be rotated by means 2, through a reducer 3, the said reducer and means 2 being mounted upon a supporting frame 4; means? carried in adjustable supports Band I, the means :5 being positioned transversely of the lap I and adapted to be reciprocated diametricallyof the lap by means 8, together with means 9, whereby grit maybe progressively fed to the surface of the lap.

Preliminarily, it may be stated that the .means 5 includes bars-provided with members for holding Work and in such a manner that during reciprocation of the means 5 and .rotation ofthe' lap l-the work is progressively played over the entire surface of the lap and in such a-manner that the lap surface is maintained at a pr-eselected angle, whether the surface be concave, convex or plane.

The frame 4 is conventional in form. and so constructed as to best support the various elements of the invention. 'In the present'instance the frame is rectangular and provided with corner legs in for longitudinal channelmembers]! and transverseimembers I'Zfthe' legs suitably 3 braced by means of webs l3. Extending between the longitudinal channel members I! are plates l4, l5 and I6, and it is upon these plates that the elements of the invention are mounted and secured.

Fastened to plate l5 by bolting or otherwise is reducer 3, which comprises a series of ears, not shown, one of which connects with shaft H for rotating the lap I. The gears in the reducer, through the medium of a shaft l8, shown in dotted lines in Fig. 1, connect with a clutch 19, the clutch in turn being connected with a shaft of the motor 2. This motor may be of small H. P. and of the type adapted to rotate approximately 1740 R. P. M., the reducer cutting down the rotative speed of the motor shaft so that the shaft I! rotates the lap at approximately 50 R. P. M. No particular type of clutch i9 is specified, although the clutch should be or the variable rotative type which allows the motor to run at a constant speed while the clutch gradually rotates the lap to its final speed. Glutches of this t pe are obtainable on the market, one of which is sold under the commercial name of Hillard. Supported by reducer casing 21 is a bearing plate 722, the said bearing plate being spaced from the reducer casing by means of adapters 23, of which there may be a plurality and through which adapters are passed bolts 24. The said bearing plate is formed with a central opening 25 through which shaft I'i is passed, and said plate is concentrically recessed at 26. The recess 26 is adapted to confine a pair of annular race members 2 and 28; between which are placed bearings 29. An annular adapter 30 is positioned between the inner race member and the periphery of shaft l1 and has a part which overlies the top of one of the race members.

The lap 11 is carried by a table 3|; This table in the present instance is circular and has substantially the same diameter as the lap. The said table is formed with an axial opening 32 and with a hub 33 on its under surface. Radial webs of decreasing depth extend from the hub 33 to the rim of said table, to give strength to the construction and prevent bending movement. The hub end rests on the adapter 39.

The lap I is held against shifting relative to the table 3| by clamps 35, see Fig. 10. These clamps include plates 36, bolted or otherwise se cured as indicated at 3'! to the edge of the table, and with a portion 36 projecting above the table top and carrying a set screw 39 This set screw is adapted to engage the edge of the lap, as indicated. A plurality of the clamps are spacedly secured to the table top; as illustrated in the several figures.

The lap I may be of any desired thickness, depending generally upon the diameter of the lap. This lap has two surfaces 4|] and 4|, both provided with radial grooves 42, the radial grooves of one surface of the lap being offset with relation to the grooves on the opposite surface, as best illustrated in Fig. 6. Certain of the grooves 42- extend diametrically of the lap surfaces, as indicated at 43, while other of the said grooves, as shown at 44 and s5, terminate outward of the center of the lap and do not intersect. It is intended that both surfaces of the lap should be used, and when one surface, as 40, has been worn down 50 that the grooves are no longer useful, the lap may be reversed to position the surface 4! on top. Such a system of course prolongs the useful life of the lap.

Secured to plates I4 and I6 are the adjustable 4 supports 6 and 1. These supports include pedestals or housings 46 and 41. As the pedestals are identically formed, one thereof will be described, the same reference characters applying to the other. The pedestal 46 is provided with a flanged base 48 which is bolted or otherwise secured to the plate I4. The tubular portion 49 of said pedestal is braced by providing webs 50 between said portion and the base. The transverse dimension of thetlibular portion 49 is enlarged at 5|, and provided with one or more transverse bores 52, see Fig. 9. One of the bores receives a screw 53, the end of which is reduced in diameter at 54.

' Adapted for adjustable movement within the tubular pedestal or housing is a slide 55. This slide is tubular in form and is provided with a series of spaced transverse perforations 56, adapted to receive the reduced end portion 54 of screw 53. The upper end of said slide 55 transversely carries a guide 51. This guide includes a base plate 58, provided with two spaced apart parallel side members 59 and 60, indicated by the dotted lines in Fig. 1. Thecover or cap 6| spans the sides 59 and 60 and is secured thereto by means-of bolts 62; This construction provides an enclosed way for movement of the bar 5. The bar 5 is an elongated rectangular=cross-sectioned member, as best illustrated in Figs. 1 and 6. a

The means 8 includes a link or Pitman 63, secured by means of a pivot pin 64 to the bar 5 and adjacent one end thereof, the opposite end of said Pitman being secured by a pivot pin 65 to a. disc 66 and adjacent the rim of said disc. The disc 66 is provided with a hub 61, keyed at 68 to a sleeve shaft 69. A solid shaft 10 is telescopically received within the sleeve shaft, the said solid shaft being provided with a longitudinal keyway ll, adapted to receive a key 12 carried by the lower end of the sleeve shaft. M The solid shaft is secured to the upper member 13 of acoupling 14, the lower member 15 of the coupling is connected to a shaft 16 leading to a gear reduction means 11. The gear reduction means in turn is adapted to be driven by a motor 18. For the sake of simplicity the drive between the gear reducing means and the motor is shown as a continuous belt 19 passed between pulley carried by the shaft of the motor and pulley 8| mounted on a shaft leading to thefgears of the gear reducing means. To support the disc 66 and its sleeve shaft are a pair of spaced apart brackets 82 and 83; one of the ends thereof is secured to the sides 59 and 60 of a guide 51, and the opposite ends 84 and 85 thereof are secured to a bearing 86 which surrounds the sleeve shaft. Between the bearing 86 and the end of the hub 61 of the disc is a washer 81, while the lower end ofsaid bearing is held in position by means of a collar 88, secured to the sleeve shaft. Any convenient means may be utilized for holding the outermost bracket ends to said bearing 86, such as by screws '89 shown in Fig. 6.

The bar 5 is provided with oneor more elongated slots 90. Carried by said bar are cross-'- bars or arms 9|. Said crossbars are provided with one or more elongated slots 92. The cross bars may be held to the bar 5 by means such as illustrated in Fig. 8 at 93. This means includes a bolt 94, adapted to receive a nut 95, the shank of said bolt being passed through a bore 96 in the crossbar and through one of the slots 96 of the bar 5, and then locked in position at some desired point by means of the nut 95. In the present instance the bore 96 is situated midway between ends of a crossbar, and the "elongated shown at 99.

"thermore, .the crossbar .is transversely positioned beneathjhe-bar 5.;1,';TI;h e crossbars may also vary as to-iength, as it will beseen that the.;crossbars shown at 91 and 98 are; shorter than the crossbar The manner of determining the proper length of crossbar'to be used and the method .of using the same will be'detailed in the statement,ofv operation. V 7 1 In order to maintain the work upon the lap I have provided means 100, the constructiomof which is detailed in Fig. 8. The saidmeans includes a pin lI, provided :with one or.more spaced ,apart annular- .grooves I 02, the said pin P 1 13 Passed through a sleeve I03 provided with a head I04, the external surface of which sleeve is screwthreaded in part at I05. The-head I04 is transversely bored at 00 to receive a spring pressed detent I01. The detent is adapted to be positioned in some one of theannular grooves I02 of, the pin. A nut I08 is carried on thethreads I05, and the said means I00 when in position of service upon one of the cross arms or bars has the base I04 engaging the under surface ofsaid barf andlstraddli'ng the slot 92.therein, with a washer1I09 lying against the opposite surfaceof said'bar. and carried on the sleeve; I03. When the nut 108 is turned the nut, washer and base arebrought into clamping relationship with the bar in thefwell understoodmanner. v

It is essential during the operation of a device of the character. at. this invention that the'surface of the'lapbesupplied with a-gritty fluid, and at H0 1 have; provided means whereby a liquid containing grit-may be constantly fed to the lap and at any desired location on said lap. The I arrangement of the deviceissuch that the flow is continuous and without clogging. The means II 0 includes a tank II I, within which is jagitator IIZ. This agitator is positioned adjac'ent to'base I I3 of the-tank'and 'extendsisubstantially diametrically thereof. The agitator includes two wing portions meeting at the apex to form af'Vfa's shown 3.13:1 I4. The agitator is centrally' secured tea shaft I I5; whichis 'pass'ed'through a guide sleevel'lfifcarriedbythe tank cover I I1- The shaft extends through the cover and exteriorly mounted thereon is'a bevel gear H8, which meshes with'bevel gear H9, mounted. on shaft f|20.this shaft being carried in" suitable bearingtype brackets I2I and I22 secured to the cover, as indicated for both brackets at I23. One end of the shaft has secured thereto a pulley wheel I24; A continuous belt is passed around the pulley wheel #24 and pulley wheel I 25 on the shaftplof a motor '523. see Fig. 2, whereby the agitator may be rotated.

Secured to shaft I I5is a wiper-I21. This wiper has .a curved arm I23. to which is attached, a g:

strip of'leather or other material I29. Secured to the side wall of the tank isafitting I30. ,This fitting has 'a tapered bore I3I and an end wall I32, provided with a transverse perforation I33. The transverse perforation I33 is of small diameter, and the arrangement is such that the leather wiper blade I29 is adapted to play over the end I32 of the fitting and constantly maintain the surface clear of any grit which might tend to build upon the surface and close the perforation I33. The said fitting is held to the container side wall in any convenient manner, such as by means I34. constituting a collar'secured to the side wall of the tank and in screwthreaded engagement with the fitting. The tank groove 43.indicated a I reciprocatedg to the-limit of its excursionin the is secured to a platform I 35, the platform in turn being on itheupper' endof a tubular stand I36, the lower end of which stand is flanged so that the same may be fastened to the plate I6 in any appropriate manner, suchas by bolts.

A wire I3|.is.secured to; th fitting in communication with the tapered bore I3I. This wire may be of extended length and positioned over the lapsurface. It has been found in practice that the grit carrying liquid will follow the wire and drop from the end thereof at'any desired location. 'It is of course obvious that any; number .offittings I30 and wires I31 may be secured to. the tank or tanks as may be necessary.

The operation, uses and advantages of the invention are as follows. a The, work may be placed within the confines of wear rings of thecharacter illustrated in Fig.3 at I38. These wear-rings are annular in form and usually made of cast iron, the material forming no part of the invention, however; Adapted forplacement within the confines ofthe wear rings and over the work I39 is workholding disc I40. Usually a felt disc MI is interposed between disc I40 and the work, as this serves to accommodate for any unevenness or variation of thickness in the work which is being lapped. The disc is formed with a central opening I 42, adapted to receive one of the pin ends of a pin IOI.; Having selected the number of wear rings necessary to hold. the work to be lapped, the crossbars are regulated relativeto the bar 5 in such a manner that when the bar 5.is reciprocated the wear rings will move over substantiallythe entire surface of the lap. Taking Fig.1 by way of example; it will be observedthat the pins are positioned in crossbar- 99- near the outermostends thereof .and the; wear rings would be positioned as indicated. The wear rings-are positioned centrally of cross:- bars 91; and 98.' In the position. of the bar 5 of Fig. 1 the .baryhas reached the limit of its excursion in Qnedirectionand the crossbarat 91 has its wear-- ring overlapping the diametrical I43. W hen the bar 5 is opposite. direction,- the bar at S'I will'be close. to the rimof the lap, or substantially in ,the position now-occupiedby the crossbar shown at 08-.

i It is not always necessary. to use awear ring. .Wear rings are usually employed when the work is of small diameter and fiat. When the work is of large diameter-and has an opening or openings therein, the pins IOI directly engage such work. However, it is essential that either the workz alone or the work Within wear rings be so located relative to the crossbar, that the work traverses the entire surface-.ofthelap. during reciprocation ofthe said bars I have found that the use of wear rings whichextend beyond the edges of the lanes indicated in Fig-. 1, is of advantage. .as itaSsures that the lap-surfaceis evenly worn. ,Otherpositions of the work may be resorted to as long as the work is so distributed as to cover the lap when the work is reciprocated across the surface of the lap. By way of example, the pins I0! might be positioned within the slots of the crossbars '91 and -98, and in place of utilizing the nut and bolt arrangement of Fig. 8, shown at 93, the pins l0! .may be substituted. Different arrangements may be resorted to, as stated, as long as the principle of the invention is adhered to, to wit: that the lap surface must be covered or substantially covered surface.

7. When the device first commences operation the motor 2 rotates the reducer 3 through the clutch is, and gradually the lap picks up speed. The motor 18 drives the gear reduction means [1, which in turn rotates the sleeve shaft and the solid shaft which are in keyed connection, to turn the'disc 8 and move the Pitman 83 to cause reciprocation of bar within its guides 51. This reciprocation will of course move the work held bythe pins over the surface of the lap and in such a manner that all areas of the lap are contacted. It is of course realized that in a lap of any diameter the speed of movement increases with the radius. As a consequence, work is not always properly dressed due to this'change in lap speed. However, by reciprocating bar 5 the work is so moved as to play over all portions of the lap and cause equal wearing of the lap.

While this operation is proceeding, the motor J20 is driving the agitator or impeller H2 within the tank to keep the grit from settling and likewise evenly distributing the grit in the tank. As the shaft H5 rotates the wiper blade constantly passes over the inlet end of the fitting 30, maintaining it free and permitting the grit laden fluid to pass into the fitting at a slow speed. The wire I37 is readily bendable so as to position the outermost end thereof in any location desired on the lap, so that the grit may be fed to such portions of the lap as may be desired. As the lap rotates and the work is ground or dressed, cuttings and other debris, including grit, are received within the radial grooves 4345 inclusive of the lap, which clears the lap surface of any substances which may tend to abrade or otherwise damage the work. The rotation of the lap, while at a low speed, nevertheless causes centrifugal action tending to direct the liquid and its cuttings outwardly toward the rim; These cuttings and fluid are received within the container type car shown in Fig. 6 at I445 A feature of the invention resides in the adjustment permitted whereby work of different sizes may be accommodated on the lap. To accomplish this adjustment the'tubular sleeve or housing 49 carries movablescrew pins 53, see Fig. 9, which engage in one of the selected transverse bores 56 in the slide 55. Thus the slides may be elevated relativeto their housings, and

then held againstmove'ment by means such as shown in Fig. 6 at I45. This means constitutes a clamp screw passed through a scr'ewthreaded enlargement on the housing, the end of which screw engages the slide. The screw pins 53 are then inserted within the proper openings in the slide, whereupon the clamp screw I45 may be released. Such movement of the slides will of course elevate the bar 5. However, such elevation does not affect the operating characteristics of the machine for the reason that the sleeve shaft 69 will move relative to the solid shaft 10, and as the two are keyed together, rotation of one 60 Number produces rotation of the other. One of the guides for the bar 5 carries bracket members 82 and 83, which support the disc 66, together with the Pitman 63; As the sleeve shaft is secured to the disc by keying, it is obvious that as the slides are elevated the sleeve shaft is moved relative to the solid shaft.

The pins I01 are adjustable as to height above the work. This adjustment permits the pins to be released from the work after a grinding operation, as well as correctly positioning the pins when for any reason the slides are elevated above thelap.

' I have previously stated that any number of fittings I30 may be provided, together with wires leading from said fittings. Thus the grit laden fluid may be conducted to the surface of the lap and at different zones of said surface as necessity requires.

I claim:

In a lapping machine; a circular lap having a working face; a bar positioned above and diametric of said lap; supports for said bar; said bar formed with a longitudinal slot; an arm transverse to said bar and adjustable pin connections between said arm and said bar and movable within the bar slot to position the arm relative to the lap surface; said arm being formed with longitudinally extending slots and adjustable pin connections passed through said slots for engaging work, said adjustable pin connections being so positioned in the slots that when the lap is rotated and the said bar is reciprocated, the work engages the entire surface of said lap to thereby produce even wear of the lap surface.

' EARL J. BULLARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Luther June 4, 1895 Buchhop et al Dec. 17, 1895 Stewart Feb. 21, 1905 Peirce Feb. 12, 1907 Florstedt Aug. 13, 1912 Hanson June 24, 1913 Root Nov. 4, 1913 Ball July 12, 1938 Kampmeiser et a1. July 8, 1941 Gleba Oct. 21, 1941 Boynton Oct. 20, 1942 Klenke Apr. 13, 1943 Wheildon June 12, 1945 Fruth July 16, 1946 FOREIGN PATENTS Country Date Great Britain 1875 Germany Aug. 7. 1905 Number 

